My 257 B3 has play in the lift arm hydraulics. It doesn't drift down with a full bucket but when back dragging or cutting grade the rams will move an inch in either direction. This makes it extremely hard to cut grade or back drag. It's like float mode but not as much play. Also when traveling with an empty bucket and I hit a decent bump the arms will do the same play and jerk around, any suggestions?
It almost sounds as if a boom cylinder rod piston nut is backed off. The piston stays seated when boom is lifted hydraulically, but pulls away when outside forces lift the boom.
So both left and right cylinders move, could that still be the case? I was thinking inner piston seals but it doesn't drift any other time. I don't know enough about hydraulics to know what goes on with the check valves, valves spools. Could any of those things cause this situation?
I`d say the pins are worn
Pins are all good, I can watch the ram go in and out while back dragging
I don't think it is a lift cylinder piston nut, because the 257B3 (assuming it's a B7H prefix) does not have them. The piston screws straight on to the cylinder rod. See below. Piston #4 screws straight on to rod #7.
Could the piston be loose from the rod?
You said it will carry a load and not noticeably drop. What if you pick the nose of the machine up with the bucket edge down. Does the machine drift down?
It will stay up and not drift down, well until I start moving then thats when it moves up and down
Cat guy told me today that only way to fix it was to bring it into their shop.....
How deep are your pockets....? Make sure you have a supply of KY with you when presented with the bill. It won't hurt - much.....
Very shallow pockets, if they were deep I would have just sent it into the dealer and waited for the the bill!! Anyone else have any ideas? I plan on having the machine down for a week at the end of June and would like to get it repaired then (if I can find the problem).
block off the lines going to one lift cylinder at a time and see what happens if you can connect the rod end and piston of disconnected cylinder with a line to contain oil spillage
does it have float mode? sounds like its in float mode setting?
Could it have air trapped in the rod end of the cylinders. Try raising the loader arms all the way up and down to see if that makes it any better
If someone can post a hydraulic schematic, we can see if there is a crossover over component, like a float valve, that may simply have a blown seal.
Something like this...
Serial Number prefix should be B7H if it is a 257B3. Problem is that there is a break at B7H01035 and the schematics are different above & below that. Need to know which group the machine falls into.
I fall into Mobiltech thinking, Air in cylinders, when lifting is already compressed, when back dragging could be a bubble that expands and compresses as the bucket rides uneven surface. Need to get the cylinders disconnected from the bucket, no load on them with fittings UP and cylinder level then drive full distance one way, loosen fitting on cylinder side with minimal Fluid in it, see if air escapes, tighten all fittings run cylinder full to stop other direction repeat the process. Farm tractors are notorious for this issue.
B7H01910
I have ran arms up and down multiple times, that was my first thought. That produced no change in operation. I will try what dmiller and mark250 has suggested next week when I get the machine back to the shop.
It does have float mode and acts like its in float mode but only moves about an inch or so instead of normal. The reason I don't think it is that is because it lifts fine and will stand it self up on the edge of the bucket.
Here's the hydraulic schematic
All I see is cylinders and main spool.
Back to Mark’s suggestion of isolating each of the lift cylinders in turn and see what happens.?
thanks for the serial number looking at the 'as shipped' list in SIS I see the hydraulic arrangement is listed as standard but the lift lines group is for the optional work tool positioner. I am not sure what is going on there but Does your machine have the automatic level switch #7 in the photo If so operate the switch to change lift option and try
ive not got the same issue but you all know what your talking about and here seems a good place to start! ive a 257b3 and have purchased a simex planer for it, issue is the planer is 5 line hydraulics and machine is 3, can you get another hydraulic line from this machine or shall i convert planer to 3 lines? thanks
Best to start a new thread. I've converted many attachments from 5 hose to 3, but, my note-taking sucks.